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Remote code execution via the `pretty` option.

Moderate severity GitHub Reviewed Published Feb 28, 2021 in pugjs/pug • Updated Apr 16, 2025

Package

npm pug (npm)

Affected versions

< 3.0.1

Patched versions

3.0.1
npm pug-code-gen (npm)
< 2.0.3
>= 3.0.0, < 3.0.2
2.0.3
3.0.2

Description

Impact

If a remote attacker was able to control the pretty option of the pug compiler, e.g. if you spread a user provided object such as the query parameters of a request into the pug template inputs, it was possible for them to achieve remote code execution on the node.js backend.

Patches

Upgrade to [email protected] or [email protected] or [email protected], which correctly sanitise the parameter.

Workarounds

If there is no way for un-trusted input to be passed to pug as the pretty option, e.g. if you compile templates in advance before applying user input to them, you do not need to upgrade.

References

Original report: pugjs/pug#3312

For more information

If you believe you have found other vulnerabilities, please DO NOT open an issue. Instead, you can follow the instructions in our Security Policy

References

@ForbesLindesay ForbesLindesay published to pugjs/pug Feb 28, 2021
Reviewed Mar 3, 2021
Published to the GitHub Advisory Database Mar 3, 2021
Published by the National Vulnerability Database Mar 3, 2021
Last updated Apr 16, 2025

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(75th percentile)

Weaknesses

CVE ID

CVE-2021-21353

GHSA ID

GHSA-p493-635q-r6gr

Source code

No known source code
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